Surface finishing machine



July 14, 1970 D. LEE 3,520,090

SURFACE FINISHING MACHINE Filed Jan. 29, 1968 2 Sheets-Sheet l h 23 3 iF W 43 7 Fig.2

//Vl N7'OR Dona/d L66 .HSLOUGH AT ORNEY July 14, 1970 D. LEE 3,520,090

SURFACE FINISHING MACHINE Filed Jan. 29, 1968 2 Sheets-Sheet 2 *5O f83/50 //VVNTOR Q57 Doncz/ Lee 52 F|$7 BY 4 1/. H. a: OUGH ATTORNEY UnitedStates Patent 0,

3,520,090 SURFACE FINISHING MACHINE Donald Lee, 3633 Straudhill Road,Shaker Heights, Ohio 44122 Filed Jan. 29, 1968, Ser. No. 701,144 Int.Cl. B24b 23/00; B24d 17/00 U.S. Cl. 51-170 7 Claims ABSTRACT OF THEDISCLOSURE This invention relates to surface treating apparatus of thetype having a rotatable member adapted to be moved across the surface tobe treated and relates more particularly to a surface finishing machinefor grinding smoothing, polishing and finishing operations.

The invention as herein disclosed comprises a hand grinder or polisherhaving a motor driven shaft which carries an eccentrically mounted pivotmember. A freely rotatable mounting plate is mounted on the pivot memberand a counterweight is also carried by the drive shaft for offsettingthe centrifugal force. caused by the eccentric throw of the mountingplate. The mounting plate carries a resilient disk and a centrallydisposed socket member adapted to receive a disk-shaped plug. The plugis adapted to snap into the socket and has a finishing disk attachedthereto whereby said disk can be quickly and easily attached to orremoved from the machine. As disclosed herein by way of illustration,the finishing disk is of the sanding or abrasive type but it will beunderstood that nonabrading disks may be used. It is anticipated that asupply of finishing disks may be provided, each having a plug attachedthereto, and it is further anticipiated that a plurality of disks may bemounted on a single plug to be successively used, as will hereinlaterbecome apparent.

Where. reference is made in the following specification and claims to asurface finishing machine or finishing machine it will be understoodthat the same is intended to cover machine adapted for grinding,abrading, smoothing, polishing and similarly treating the surface ofmetal, wood, plastic or the like. Use of the term finishing or finishingdisk refers to materials for use in effecting the above-referred togrinding, abrading, smoothing, polishing and similar operations.

In general, the object of this invention is to provide a surfacefinishing machine which has improved balance in operation, easierhandling characteristics, simple means for quickly and easily removingand replacing the finishing material, and is simple, sturdy, and durablein construction.

More specifically, it is an object of this invention to provide asurface finishing machine of the type set forth above wherein the freelyrotatable mounting plate is cupshaped having an upturned peripheralflange and wherein the counterweight is disposed entirely within the cupshaped mounting plate to lower the center of gravity of the machine.

Another object of the invention is to provide a surface finishingmachine of the type referred to having improved means for quickly andeasily attaching or removing a finishing disk to the mounting platethereof.

Still another object of the invention is to provide a surface finishingmachine as set forth above having a downwardly open socket in the centerof the rotating 3,520,090 Patented July 14, 1970 ice member and a plugadapted to snap fit into said socket, the plug having a finishing disksecured thereto.

Another object of the invention is to provide the aforesaid plug andsocket construction wherein the plug constitutes a throwaway item to besupplied with new finishing disks.

Yet another object of the invention is to provide a plug as set forthabove having a finishing disk adhesively secured thereto at tile centerof said disk.

A further object of the invention is to provide a plug having afinishing disk attached thereto and additional finishing disksoverlapping and detachably secured to the first mentioned disk.

A still further object is to provide finishing disk attachment means asset forth above wherein each disk is provided with a strip of pressuresensitive adhesive on its upper surface adjacent to the outer edgethereof and a corresponding plain surface portion on its lower surfacewhereby a number of finishing disks can be secured together and carriedby a single plug to be peeled off as they are worn out.

Other objects of the invention and the invention itself will be apparentfrom the following detailed description of the invention and theaccompanying drawings, in which said drawings:

FIG. 1 is a top plan view of the surface finishing machine of thisinvention;

FIG. 2 is a section taken along the 1ine.2-2 of FIG. 1;

FIG. 3 is a section taken along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged perspective view of a socket member;

FIG. 5 is an enlarged perspective view of a plug adapted to snap fitinto said socket member;

FIG. 6 is an exploded enlarged detail view in cross section of thesocket, plug, and associated parts; and

FIG. 7 is an exploded section through peripheral edge portions ofmodified forms of the finishing disk.

Referring now to the drawings in all of which like parts are designatedby like reference numerals and particularly to FIGS. '1, 2 and 6, the.surface finishing machine of this invention is generally indicated at 10and comprises a housing 11 having a motor 12 mounted therein. The motor12 is a conventional electric motor and is mounted upon a vertical axiswhereby the drive shaft 13 thereof projects downwardly. The lower end ofthe drive shaft 13 is threaded as indicated at 14 whereby it is adaptedto be thread fitted into a boss 15 of a counterweight 16. The boss 15 ofsaid counterweight also carries an eccentric pivot pin 17 which isthread fitted upwardly into the :boss and carries a freely rotatable,cup shaped mounting plate 18. Said mounting plate includes a resilient,disk shaped backup member 19 secured to the lower surface of themounting plate 18 in any suitable manner; and a surface. finishing disk20 is detachably secured to the lower surface of the backup member 19 bya socket and plug assembly generally indicated at 21.

From the foregoing, it will be readily apparent that the mounting plate18, backup member 19, and finishing disk 20 all move together in aneccentric path around the drive shaft 13 with the recited member beingfreely rotatable during such eccentric movement about a common axis.

As herein shown, the housing 11 is preferably a casting made of asuitable metal, plastic or other suitable material, having an upwardlytapered body portion 22 and a radially outwardly disposed skirt 23 atits lower end. A first gripping handle 24 projects laterally andupwardly from the skirt 23 by means of arms 25. A second gripping handle26 is cast into the upper end wall 27 of the body portion 22. Anoperator of the machine of this invention grasps the first grippinghandle 24 in one hand while engaging the second gripping handle 26 withthe other hand for full control and manipulation of the machine over thesurface being treated.

The motor 12 is mounted within the body portion 22 in a conventionalmanner by means of a plurality of elongated bolts 28 which projectdownwardly through inner bosses 29 and through peripheral edge portionsof said motor.

As shown in FIG. 3, the counterweight 16 has a semicircular, symmetricalweight portion 30 which projects toward the left in FIG. 2 or in adirection with respect to the drive shaft 13 which is opposite to theeccentric pivot pin 17. The mounting plate 18 has an upstandingperipheral flange 31 surmounted at its upper edge by a circumferentiallycontinuous, radially outwardly projecting flange 32. The flanges 31 and32 are disposed entirely Within the peripheral skirt 23 whereby only abottom wall 33 of said mounting plate projects slightly below saidskirt.

FIG. 3 illustrates the manner in which the weight portion 30 of thecounterweight 16 is always disposed diametrically opposite the eccentricthrow of the mounting plate 18 whereby the centrifugal force of theeccentric movement of said mounting plate is effectively counterbalancedat all times by said weight portion. It will be further noted that saidweight portion 30 is disposed entirely within the cup shaped mountingplate 18 whereby the center of gravity of the entire machine is keptsubstantially low.

The bottom wall 33 of the mounting plate 18 has a centrally disposed,upwardly projecting boss 34 which is centrally recessed at 35 to receivea ballbearing member 36 (FIGS. 2, 6). Said ballbearing member isretained within the recess 35 by means of a plurality ofcircumferentially spaced screws 37 disposed around the outer edgeportion of the boss 34 with their heads overlapping an outer raceportion 36a of said ballbearing member.

In the bottom of the recess 35, the bottom Wall 33 has a throughaperture 38 which is adapted to receive a downwardly open cylindricalsocket 39. Said socket has an upper end wall 40 which is disposed belowthe ball bearing member 36 and an inner circumferential wall surface 41which converges slightly in an upward direction. The lower end of saidpivot pin is provided with an enlarged head 42 which overlaps an innerrace portion 36b of the ballbearing member 36 whereby the mounting plate18 is rotatably mounted upon said pivot pin.

As shown in FIGS. 2 and 6, the resilient backup member 19 has afrustoconical, concave recess 43 centrally of its bottom surface, thelower edges of the socket 39 terminating at the bottom of said recess43. A slightly upwardly tapering plug 44, detailed in FIGS. 5 and 6, isadapted to snap upwardly into the downwardly open socket 39. Said plug44 is disk shaped and is provided with a radially outwardly projecting,circumferentially continuous flange 45 at its lower end which isslightly larger in diameter and radially outwardly overlaps the loweredge of the socket 39. A finishing disk 20 is glued, bonded, orotherwise suitably secured to the bottom surface of the plug 44 wherebywhen said plug is snap fitted into the socket 39, said finishing disk iscarried against the bottom surface of the flexible member 19 and rotatestherewith. Thus, no part of the plug 44 is exposed to contact the worksurface in use of the surface finishing machine 10. The socket 39 andplug 44 may be made of any suitable material, and as herein illustratedthe parts are made of plastic.

The plug 44 is designed to be a small, inexpensive member, one of whichmay be provided for each finishing disk 20 to be thrown away when thedisk is worn out. It is anticipated that said finishing disks would besupplied each mounted upon a plug whereby a user of the finishingmachine of this invention need only snap off the old, worn-out finishingdisk and snap a new one into place. By exerting only moderate pressureupon the plug, said plug will seat firmly within the socket bringing theflange 45 against the lower peripheral edge of the socket 39 ,Themodification of FIG. 7 shows the manner in which a plurality offinishing disks can be mounted upon a single plug 44 to be successivelyused and, when worn out, peeled away from the remaining disks. Themodified finishing disks are indicated at 50, each disk having surfacefinishing means such as an abrasive material 51 on the lower sidethereof. An annular plain surface portion 52-is provided at the outerperiphery of each disk around the, abrasive material 51, and an annularstrip 53 of pressure sensitive adhesive is disposed on the upper surfaceof each disk immediately above said annular plain surface portion. Itwill be readily seen that a plurality of finishing disks 50 may beremovably attached to each other by pressing the strips 53 of pressuresensitive adhesive against the annular plain surface portions 52, itbeing understood that the uppermost disk would be secured to a plug 44as described above. As each successive disk is worn out, it can bereadily peeled from the bottom of the stack.

From the foregoing it will be seen that the present invention affords afinishing machine which is easily and comfortably held and manipulated,has a low center of gravity for low, relatively vibration freeoperation, and provides means for quickly and easily renewing theabrasive surface thereof.

It will be understood that many changes in the details of the inventionas herein described and illustrated may be made without, however,departing from the spirit thereof or the scope of the appended claims.

What is claimed is:

1. In a surface finishing machine, a motor having a downwardlyprojecting, vertical drive shaft; a horizontal cup shaped mounting platehaving an upturned peripheral flange; said mounting plate freelyrotatably mounted upon eccentric pivot means disposed laterally of andparallel with said drive shaft; means connecting said drive shaft andsaid pivot means whereby said pivot means and mounting plate are rotatedin an eccentric path with respect to said drive shaft; counterweightmeans rigidly mounted with respect to said drive shaft and projectingfrom the side of said drive shaft opposite to said eccentric pivotmeans; said counterweight means being disposed entirely within said cupshaped mounting plate in a horizontal plane coplanar with said meansconnecting said drive shaft and said pivot means; said mounting plateincluding resilient backup means for a disk of surface finishingmaterial; and means for detachably mounting surface finishing materialto the bottom surface of said backup means.

2. In a surface finishing machine as set forth in claim 1: said meansfor detachably mounting said finishing material comprising a downwardlyopen socket member carried by said mounting plate; a plug member; afinishing disk carried by said plug member; said plug member having aportion thereof adapted to snap fit into said socket.

3. In a surface finishing machine as set forth in claim 1: said meansfor detachably mounting said finishing material comprising a downwardlyopen substantially cylindrical socket member carried by said mountingplate and opening at the center of said backup member; a plug memberhaving a finishing disk attached thereto; said plug member having asubstantially cylindrical portion adapted to snap fit into said socketto attach said finishing disk to the bottom surface of said backupmember.

4. In a surface finishing machine as set forth in claim 1: said meansfor detachbly mounting said finishing material comprising a downwardlyopen substantially cylindrical socket member carried by said mountingplate and opening at the center of said backup member; a disk shapedplug member having a radially projecting flange at the lower endthereof; a finishing disk secured coaxial- 5 1y to the bottom surface ofsaid disk shaped plug; said plug having a substantially cylindricalportion adapted to snap fit into said socket member whereby said flangeis seated against the lower edge of said socket member and saidfinishing disk is detachably secured to said resilient backup means.

5. In a surface finishing machine as set forth in claim 4: saidsubstantially cylindrical portion of said plug and the inner wallsurface of said socket member being tapered slightly in an upwarddirection.

6. In a surface finishing machine as set forth in claim 4: saidfinishing disk being glued to the bottom surface of said plug.

7. In a surface finishing machine as set forth in claim 1: said meansfor detachably mounting said finishing material comprising a downwardlyopen socket member carried by said mounting plate; a plug member; aplurality of coaxial finishing disks carried by said plug member; afirst of said disks being secured coaxially to the bottom surface ofsaid plug; at least the other of said disks having annular strips ofpressure sensitive adhesive on the top surfaces thereof adjacent to theouter peripheral edges thereof; all of said disks having annular plainsurface portions on the bottom surfaces thereof aligned with said stripsand all of said disks being pressed together whereby said disks can besequentially used and successively peeled from the stack of disks anddiscarded as each disk is worn out.

References Cited UNITED STATES PATENTS 2,626,489 1/1953 Thompson 51-39lX 2,991,596 7/1961 Walters 51376 1,587,843 6/1926 Koreneff 51170.2 X

FOREIGN PATENTS 496,898 8/1954 Italy.

JAMES L. JONES, JR., Primary Examiner US. Cl. X.R.

